#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<vector>
#include<cstring>

using namespace std;
bool check(vector<int>& A, vector<int>& B)
{
    if (A.size() != B.size()) return A.size() > B.size();
    for (int i = A.size() - 1; i >= 0; i--)
    {
        if (A[i] != B[i])  return A[i] > B[i];
    }
    return true;
}
vector<int> sub(vector<int>& A, vector<int>& B)
{
    vector<int> C;
    int t = 0;
    for (int i = 0; i < A.size(); i++)
    {
        t = A[i] - t;
        if (i < B.size()) t -= B[i];
        C.push_back((t + 10) % 10);
        if (t < 0)   t = 1;
        else        t = 0;
        while (C.size() > 1 && C.back() == 0) C.pop_back();

        return C;

    }
}
int main()
{
    string a, b;
    cin >> a >> b;
    vector<int> A, B;
    for (int i = a.size() - 1; i >= 0; i--) A.push_back(a[i] - '0');
    for (int i = b.size() - 1; i >= 0; i--) B.push_back(b[i] - '0');
    if (check(A, B))
    {
        auto C = sub(A, B);
        for (int i = C.size() - 1; i >= 0; i--) cout << C[i];
    }
    else
    {
        auto C = sub(B, A);
        printf("-");
        for (int i = C.size() - 1; i >= 0; i--) cout << C[i];
    }
    return 0;
}